Food preparation apparatus constructed with a view to providing either uniform temperature along a substantial surface area or substantially uniform temperature in several different areas ordinarily involves a plurality of individual heat source elements and a corresponding plurality of temperature control elements, or means to circulate heat by natural or forced convection.
A relatively large cooking surface is typically heated by locating individual heat sources adjacent one side of a thick plate and providing a control element for each heat source. Separate control elements result in apparatus which does not conveniently lend itself to automatic control. Further, the surface or surfaces being heated tend to be characterized by hot spots opposite each heating unit. The tendency to form hot spots may be reduced as a function of increased plate thickness. A relatively thick plate, however, results in an undesirably heavy apparatus which responds slowly to temperature change.